Many fuel cell power plants mounted in vehicles use a stack of polymer electrolyte fuel cells (PEFC). In this type of fuel cell, an electrolyte membrane must always be maintained in the wet state, so it is essential to supply it with water. It is also necessary to humidify fuel and air supplied to the polymer electrolyte fuel cell, and water is further used for cooling of the power plant.
Therefore, a considerable amount of water is used inside the power plant. If the outside temperature of the power plant drops below freezing point when it is not operating, this water will freeze, so undesirable effects may occur, i.e., the electrolyte membrane in the fuel cell stack may be damaged, or the startup time of the power plant may be lengthened.
Regarding this problem, Tokkai 2000-315514 published by the Japanese Patent Office in 2000 discloses an antifreeze apparatus for a fuel cell power plant. The apparatus collects water in a water passage of the power plant into a tank when the power plant terminates operation at low temperature, and supplies high temperature steam to the water passage when the power plant starts again to thaw the frozen water remaining in the water passage.